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Re: X4 155 pump conversion

Think of it this way, crimp the hose. What happens then? The pump shoe is upstream. Your talking about a reduction nozzle. Without getting into fluid dynamics, thats the best answer I have. Now, kawi did try this in the ultra 150 pump. the yield was, IMO, better top end at the expense of acceleration. but it didnt stick and we havent seen a pump like it since.

No offense, but you havent thrown the motor at your setup yet. I hope you continue to have great results, but I have a feeling youll see what Im talking about once you get the motor back from TJ and put big carbs on it.

Re: X4 155 pump conversion

Having dealt with the 140 shoe...... if I was going to do it over again, I would glass in a 155 shoe and make it work. That way it could be changed quickly and you don't need a sh1t load of silicone to seal it. Justin's set up works great..... until you need to pull the pump and pitch a prop. Ask him his routine for gettng his pump out, lol.

Basic answer, there is no 'easy' way to do it right. There is an 'easy' way to get it on the water and that is the 148 skat, just be willing to bone up the money.

Having said that, I have a stock 140 shoe that has been machined to accept the 155 pump and I have a 155 pump that has been cut (you have to do this with the stock plastic pump) that I will sell to anyone wanting to do the conversion. I have a 100 bucks of machining in the shoe and the pump is probably not work much. $200 plus shipping takes it all.

SM

Last edited by Scottie Mac; 02-03-2017 at 11:40 AM.

Those who have done the least in the sport are always the ones with the most to say.

Re: X4 155 pump conversion

Originally Posted by jdakrt

No offense, but you havent thrown the motor at your setup yet. I hope you continue to have great results, but I have a feeling youll see what Im talking about once you get the motor back from TJ and put big carbs on it.

None taken Justin. For the record the motor was far from bone stock when I was running it. I'm already running head, 44's, ignition advance, pipe mod, 41mm bore, etc. The only change this year will be prop and port. I personally didn't feel like I was pump limited with the 12 vein 148 but I'm also not nearly as knowledgeable as you guys, and in all fairness I was far from being completely dialed in. I already had so much time and effort in the ski rebuilding from the ground up that I didn't feel like tackling a 155 mod at the same time.

If someone could definitively say the 155 was a night and day difference (for rec riding) over the 148 I'd be all over it.

Re: X4 155 pump conversion

Riding both Justin's and Robinson's skis (155 conversion vs 148 skat) I think Justin's has better bottom end and midrange. Justin's ski is a beast from bouy to bouy. On top end, their two skis were pretty close - both being in the 66-67mph range.

I don't know that there is enough difference in the bottom end hit to change if you already have a 148, but if building from scratch and are willing to do the work, the 155 is a better bang for the buck set up for sure.

Scottie

Those who have done the least in the sport are always the ones with the most to say.

Re: X4 155 pump conversion

Hey Scottie, will you post pics of your machined pump shoe? Im still trying to decide on the best way to open mine up. I was thinking about removing the lip on the pump shoe so I can center the pump without having to cut into the pump at all. But, I was kind of concerned about blowing out the neoprene seal if I went that route. Not sure if that would happen or not though since the pump will be applying an inward force on the seal. After that I would remove material all around and taper it down to nearly the mounting holes for the intake grate. I grabbed some pics off of ebay and did a quick sketch showing what I'm talking about. Think this will work?

Re: X4 155 pump conversion

The pump and shoe are over at my brother's house, I will try to run by there and pick them up one day this week. Nice thing about having a machine shop do it, you can make sure the hole is perfectly round, etc. There is also a recess you need to keep for the pump to 'sit' in.

Scottie

Those who have done the least in the sport are always the ones with the most to say.

Re: X4 155 pump conversion

Originally Posted by WhiskeyD

Is this to make the pump fit flat against the pump shoe or to widen the intake tract?

Any chance you have a picture of this?

Both. I am referring to the fiberglass thats above the aluminum ring. picture the top 1/3 of the intake tract. I dont have a pic, and its a NIGHTMARE witha 4' prybar to get the pump out of my boat. Not gonna happen.... post a pic of your pump tunnel and i'll mark it up.

I believe that's what I'm wanting to remove. The curvature matches the 140mm pump but it's not wide enough for the 155mm and it hits the bottom half of the pump face.

on my skat 155, you keep about 1/8" of the lip, for the pump face to sit in and align to.

Re: X4 155 pump conversion

Originally Posted by jdakrt

Both. I am referring to the fiberglass thats above the aluminum ring. picture the top 1/3 of the intake tract. I dont have a pic, and its a NIGHTMARE witha 4' prybar to get the pump out of my boat. Not gonna happen.... post a pic of your pump tunnel and i'll mark it up.

on my skat 155, you keep about 1/8" of the lip, for the pump face to sit in and align to.

Gotcha, thanks. I was hoping to not have to cut into that fiberglass lip above that section. Plus having the pump being a PIA to get off maybe I should consider rigging up the 155 pump shoe. I've got a complete GSXL and XPL to take parts from